A ladder is disclosed in U.S. Pat. No. 4,199,040, issued Apr. 22, 1980, entitled Ship Ladder, and assigned to the same assignee as this invention, which comprises a single stringer or central tread support disposed between upper and lower levels at a predetermined angle of inclination and having an array of half treads on each side of the stringer, each array being vertically spaced from the other along the length of the stringer. The half treads are affixed to and laterally extend from the respective sides of the stringer, and each includes an integral outwardly extending portion which terminates in a plane which is forward of a plane passing through the front edges of the treads. First and second handrails are disposed in this forward plane and are affixed to and supported by the outwardly extending tread portions. This novel ladder can be disposed at a relatively steep angle in comparison to a conventional ladder of the same tread width and riser height and provides sufficient safety and comfort to permit balanced use of the ladder, even without holding onto the handrails.
Ladders are known in which treads or rungs are alternately arranged along a single stringer or pole. In ascending and descending ladders of this known type, a user must face the ladder and support himself by holding onto the rungs to guide his ascent or descent. Such ladders of known construction cannot be descended facing forward, as with a stairway, and these known ladders also require a fair degree of dexterity on the part of a user and are not very comfortable to use.